In recent years, organic electroluminescent elements (hereinafter also referred to as “organic EL elements”) have been used in the applications of illumination panels or the like. Known has been an organic EL element in which a first electrode, an organic light-emitting layer composed of a plurality of layers including a light-emitting layer, and a second electrode paired with the first electrode are stacked on a surface of a first substrate such as a glass substrate in this order. In the organic EL element, a bottom emission structure in which light produced in the organic light-emitting layer is extracted outside through the first substrate or a top emission structure in which light is extracted outside through the opposite of the first substrate can be employed. In the organic EL element with the bottom emission structure, light produced in the organic light-emitting layer by applying voltage between the first electrode and the second electrode is extracted outside through the first electrode and the first substrate with light transmissive properties. It is also known to provide a light-outcoupling layer between the first electrode and the first substrate with light transmissive properties to increase light-outcoupling efficiency.
Since the organic light-emitting layer in the organic EL element can easily deteriorate due to moisture, it is important to prevent moisture from intruding to the inside of the organic EL element and to remove unprevented moisture. Deterioration of the organic light-emitting layer due to moisture causes light emission deficiency, leading to lowered reliability of the organic EL element.
Considering the above, in order to block moisture intrusion from outside, the first electrode, the organic light-emitting layer, and the second electrode are conventionally sealed with a second substrate which is bonded to the first substrate with an adhesive and thus shielded from outside.
However, there exists a problem that only providing the second substrate is not enough to completely block moisture intrusion from outside, since the adhesive used for bonding the first substrate and the second substrate may allow moisture to permeate.
When a substance with relatively high moisture permeability such as plastic is used as the light-outcoupling layer in the organic EL element with the bottom emission structure, there also exists a problem of moisture intrusion into the organic EL element through the substance.
JP 2003-142262 A discloses an organic EL display in which a seal layer and a resin layer containing a dispersed drying agent are formed between an electrode and a substrate. However, the organic EL element in this literature is sealed with the seal layer on the substrate and the resin layer granted with a sealing function due to a dispersed drying agent, which cannot adequately improve both of moisture prevention into the organic EL element and light-outcoupling efficiency at the same time.